Pest profile

Imperial Moth

Eacles imperialis · Lepidoptera: Saturniidae[3]

The imperial moth is one of the largest moths in the Southeast, mostly yellow with brown spots and splotches; its caterpillars grow 3 to 5 inches long on pines, oaks, maples and other trees but are rarely common enough to matter.[1][2]

Imperial moth resting on a tree trunk, its wings yellow with brown spots and bands
Imperial moth resting on a tree trunk, its wings yellow with brown spots and bands. (c) Susan Blayney, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Adults are large, mostly yellow moths with light to dark brown spots, lines and blotches; males have more feathery antennae, and they usually fly at night.[1]
  • Mature caterpillars are fat, green to brown or nearly black, 3 to 5 inches long, covered in fine hair, with knobs behind the head and spots down each side.[1]
  • Newly hatched caterpillars are orange with conspicuous black spines.[1]

Where it lives

It is one of the largest moths in the Southeast; NC State notes one generation further north and possibly two in North Carolina.[1][2]

US map: public records from 31 states since 1990 (GBIF).

Biology and life cycle

Moths emerge from the soil in late spring, and females lay hundreds of eggs on many kinds of trees.[1]

Full-grown caterpillars climb down and burrow into the soil to pupate; the pupae spend the winter there.[1][2]

Few survive: caterpillars feeding in the open are eaten by birds and attacked by parasites and diseases.[1]

Damage and signs

  • Caterpillars prefer pines, oaks, maples, sassafras and sweetgum, with cedar, elm, persimmon, hickory, beech, honeylocust and cypress less common hosts.[1][2]
  • Because they are usually rare, often the only sign is frass pellets falling on pavement under the tree.[1]

Health risk

NC State and Clemson describe it only as a leaf feeder and note no health concerns.[1][2]

Control

Prevention

NC State says it seems a pity to use an insecticide on such usually rare caterpillars.[1]

Common questions

What is the huge yellow moth on my wall?
Likely an imperial moth, one of the largest moths in the Southeast.[1][2]
What is the giant green caterpillar walking across the driveway?
Possibly a full-grown imperial moth caterpillar climbing down to burrow into the soil and pupate.[1][2]
Do I need to kill imperial moth caterpillars?
Usually not; they are rare and seldom do noticeable damage.[1]

Sources

  1. NC State Extension, “Imperial Moth (PDIC Factsheet).” content.ces.ncsu.edu/imperial-moth (accessed 2026-10-15)
  2. Clemson Cooperative Extension, Home & Garden Information Center, “What Is It? Wednesday – Imperial Moth Caterpillar (Nov. 9, 2022).” hgic.clemson.edu/what-is-it-wednesday-imperial-moth-caterpillar/ (accessed 2026-10-15)
  3. iNaturalist, “Eacles imperialis taxon page (order and family).” www.inaturalist.org/taxa/81590 (accessed 2026-10-06)

Updated 2026-10-15. Built from sourced records. Spot an error? Tell us.